The present invention relates to internal combustion engines and more particularly to methods and arrangements for reducing the amount of quench layer combustibles (primarily hydrocarbons) exhausted from the combustion chambers through the exhaust system by recirculating some of these combustibles to the engine intake through their timed ejection from the combustion chambers to peripheral collection and recirculating means.
It has been generally recognized that a significant cause of hydrocarbon emissions in the exhaust gases of spark ignition internal combustion engines is the carrying out with the exhaust products of combustibles remaining along the walls of the combustion chambers after combustion has ceased. These combustibles are considered to result from flame quenching along the relatively cold walls of the combustion chambers which prevents the completion of the combustion process along the surface of the walls, leaving a layer of unburned and partially burned products, known as the wall quench layer. In the exhaust process, this layer of combustibles is partially stripped from the walls by upward movement of the engine piston, or other means, and is mixed with the exhaust gases passing into the engine exhaust system.